# Postoperative Acute Kidney Injury After Intraoperative Hypotension in Major Risk Procedures

## TL;DR

This study finds that low blood pressure during surgery is common but not strongly linked to kidney injury or death, while kidney injury itself is associated with higher mortality.

## Contribution

The study provides new insights into the relationship between intraoperative hypotension and postoperative acute kidney injury in high-risk non-cardiac surgeries.

## Key findings

- Intraoperative hypotension occurred in 56.3% of patients, with longer surgeries and certain anesthesia types increasing the odds.
- Postoperative acute kidney injury was found in 14.9% of patients and was significantly linked to higher 30-day mortality.
- Intraoperative hypotension was not significantly associated with postoperative acute kidney injury or mortality.

## Abstract

Background

Reportedly prevalent, intraoperative hypotension (IOH) is linked to kidney injury and increased risk of mortality. In this study, we aimed to assess IOH incidence in high-risk non-cardiac surgery and its correlation with postoperative acute kidney injury (PO-AKI) and 30-day postoperative mortality.

Methodology

This retrospective cohort study included adult inpatients who underwent elective, non-cardiac, high-risk European Society of Anaesthesiology/European Society of Cardiology surgery from October to November of 2020, 2021, and 2022, excluding cardiac, intracranial, or emergency surgery. IOH was primarily defined by the 2022 Anesthesia Quality Institute. PO-AKI was defined as an increase in serum creatinine ≥0.3 mg/dL within 48 hours, the need for dialysis in dialysis-naïve patients, or the documentation of AKI in clinical records. For univariate analysis, the Mann-Whitney U test and chi-square or Fisher’s exact tests were performed, as appropriate. Logistic regression was used to test risk factors for IOH in univariate analysis (p < 0.1). The significance level considered in multivariate analysis was 5%.

Results

Of the 197 patients included, 111 (56.3%) experienced IOH. After adjustment, surgical time >120 minutes remained associated with higher odds of IOH (odds ratio (OR) = 9.62, 95% confidence interval (CI) = 2.49-37.13), as well as combined general + locoregional (vs. general OR = 3.41, 95 CI% = 1.38-8.43, p = 0.008; vs. locoregional OR = 6.37, 95% CI = 1.48-27.47). No association was found between IOH and 30-day postoperative mortality (p = 0.565) or PO-AKI (p = 0.09). The incidence of PO-AKI was 14.9% (27 patients), being significantly associated with higher 30-day postoperative mortality (p = 0.018).

Conclusions

Our study highlights the high prevalence of IOH in high-risk non-cardiac surgical procedures. Its impact on PO-AKI and 30-day postoperative mortality appears less pronounced compared to the significant implications of PO-AKI, emphasizing the need for PO-AKI screening and renal protection strategies.